Where Mitt Romney, Sen. Scott Brown stand on various issues

The Associated PressIn this photo taken Jan. 19, 2010, former Massachusetts Gov. and presidential hopeful, Mitt Romney, right, introduces and congratulates U.S. Senator-elect Scott Brown, R-Mass. at his Boston victory party after he won the seat vacated by the late Sen. Edward Kennedy. The two Massachusetts Republicans have a history of supporting each other throughout their political careers, but facing tough elections neither is playing up that history now, perhaps with good reason. (AP Photo/Elise Amendola)

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Republican presidential hopeful Mitt Romney and U.S. Sen. Scott Brown publicly support each other and even share key advisers. But on many topics, from foreign policy to social issues, the Massachusetts Republicans take very different positions.

ABORTION:

Romney opposes abortion rights and says the Roe v. Wade Supreme Court decision that legalized abortion should be reversed so states can be free to craft their own abortion laws.

Brown opposes federal funding for abortions, but thinks women should have the right to choose to have the procedure. Opposes efforts to overturn Roe v. Wade.

GAY MARRIAGE:

Romney opposes gay marriage and signed a pledge supporting a federal constitutional amendment to define marriage as between a man and a woman.

Brown opposed gay marriage as a state lawmaker. Says he doesn't support the proposed federal constitutional amendment.

DON'T ASK, DON'T TELL:

Romney, in 2007, said the policy barring gay members from serving openly in the military seemed to be working. He said the middle of a war wasn't the time for "a social experiment." The policy was repealed in 2011.

Brown, who has served more than three decades in the Army National Guard, joined Democrats and some Republicans in voting to end the policy.

TAX RETURNS:

Romney has been reluctant to release more than two years of his tax returns.

Brown has made public six years of his tax returns.

FINANCIAL OVERHAUL:

Romney has called for repeal of the Dodd-Frank law that sought to toughen financial-industry regulations after the 2008 meltdown.

Brown was among just three Republicans who voted for the bill, which also created the new Consumer Financial Protection Bureau.

NUCLEAR ARMS TREATY:

Romney has said the START treaty to further limit U.S. and Russian nuclear arsenals was President Barack Obama's "worst foreign policy mistake yet."

Brown voted for the treaty but said more work was needed to curb tactical nuclear weapons in Russia and nuclear proliferation in Iran and North Korea.

OBAMA:

Romney, as the presumptive Republican presidential nominee, points out every shortcoming he sees in Obama's record.

Brown may be one of the few Republicans to go out of his way to highlight areas of agreement with Obama, who remains popular in heavily Democratic Massachusetts.